CN116165813A

CN116165813A - Optical modulator and method of forming the same

Info

Publication number: CN116165813A
Application number: CN202310003328.8A
Authority: CN
Inventors: 陈代高; 肖希; 刘敏; 刘佳; 刘晔; 周佩奇; 刘阳; 胡晓; 张红广
Original assignee: Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
Current assignee: Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2023-05-26

Abstract

Embodiments of the present disclosure provide an optical modulator and a method of forming the same, the method comprising: forming an initial doping layer on the dielectric layer; etching a first preset region of the initial doping layer to form an initial first waveguide, and etching a second preset region of the initial doping layer to a preset height to form an etched second preset region; forming an initial second waveguide based on the etched second preset region; p-type doping is respectively carried out on the initial first waveguide and the etched first preset region, and a first waveguide and a P-type doped region are correspondingly formed; respectively carrying out N-type doping on the initial second waveguide and the etched second preset region to correspondingly form a second waveguide and an N-type doped region; the first waveguide and the second waveguide form a ridge waveguide, and the P-type doped region and the N-type doped region form a doped layer; and forming a covering layer covering the ridge waveguide on the doped layer.

Description

Optical modulator and method of forming the same

Technical Field

The present disclosure relates to the field of semiconductor technology, and relates to, but is not limited to, an optical modulator and a method of forming the same.

Background

The silicon-based photonic chip has the advantages of compatibility with standard semiconductor technology, low cost and high integration level, and is gradually widely adopted in the industry. The modulator is one of the most core optical devices in a silicon-based photonic chip. At present, a high-speed silicon-based optical modulator usually adopts a modulation structure of a horizontal PN junction, a PN junction is formed near the central line of a waveguide by P-type doping and N-type doping, and the width of a depletion region can be adjusted by applying reverse bias voltage to the PN junction, so that the adjustment of the refractive index of the waveguide is realized. According to the current simulation result, the modulation efficiency of P-type doping for light is higher than that of N-type doping, so in order to obtain higher modulation efficiency, it is common practice to place a PN junction near one side of N-type doping, i.e. to make P-type doping occupy a larger cross section in the waveguide. However, the improvement in modulation efficiency obtained by this scheme is limited.

Disclosure of Invention

In view of the foregoing, embodiments of the present disclosure provide an optical modulator and a method of forming the same.

The technical scheme of the present disclosure is realized as follows:

in a first aspect, embodiments of the present disclosure provide an optical modulator, comprising in order: the device comprises a dielectric layer, a doped layer, a ridge waveguide positioned on the doped layer, a cover layer positioned on the doped layer and coating the ridge waveguide, and a first electrode and a second electrode which penetrate through the cover layer and are electrically connected with the doped layer, wherein the first electrode and the second electrode are formed by the dielectric layer, the doped layer, the ridge waveguide positioned on the doped layer, the cover layer positioned on the doped layer and coating the ridge waveguide, and the first electrode and the second electrode which penetrate through the cover layer and are electrically connected with the doped layer, wherein the first electrode and the second electrode are formed by the dielectric layer, the doped layer, the ridge waveguide and the first electrode are formed by the cover layer. The doped layer comprises a P-type doped region and an N-type doped region which are arranged in parallel; the ridge waveguide comprises a first waveguide arranged on the P-type doped region and a second waveguide arranged on the N-type doped region, wherein the first waveguide and the second waveguide are both made of semiconductor materials, and the refractive index of the first waveguide material is larger than that of the second waveguide material.

In a second aspect, embodiments of the present disclosure provide a method of forming an optical modulator, the method comprising: forming an initial doping layer on the dielectric layer; etching a first preset region of the initial doping layer to form an initial first waveguide, and etching a second preset region of the initial doping layer to a preset height to form an etched second preset region; forming an initial second waveguide based on the etched second preset region; p-type doping is respectively carried out on the initial first waveguide and the etched first preset region, and a first waveguide and a P-type doped region are correspondingly formed; respectively carrying out N-type doping on the initial second waveguide and the etched second preset region to correspondingly form a second waveguide and an N-type doped region; the first waveguide and the second waveguide form a ridge waveguide, and the P-type doped region and the N-type doped region form a doped layer; and forming a covering layer covering the ridge waveguide on the doped layer.

In an embodiment of the present disclosure, an optical modulator includes, in order from bottom to top: the device comprises a dielectric layer, a doped layer, a ridge waveguide positioned on the doped layer, a cover layer positioned on the doped layer and coating the ridge waveguide, and a first electrode and a second electrode which penetrate through the cover layer and are electrically connected with the doped layer; firstly, forming an initial doping layer on a dielectric layer; secondly, etching a first preset area of the initial doping layer to form an initial first waveguide, and etching a second preset area of the initial doping layer to a preset height to form an etched second preset area; thirdly, forming an initial second waveguide based on the etched second preset area; then, P-type doping is carried out on the initial first waveguide and the etched first preset region respectively, and a first waveguide and a P-type doped region are correspondingly formed; respectively carrying out N-type doping on the initial second waveguide and the etched second preset region to correspondingly form a second waveguide and an N-type doped region; the first waveguide and the second waveguide form a ridge waveguide, and the P-type doped region and the N-type doped region form a doped layer; finally, a cover layer is formed on the doped layer to cover the ridge waveguide.

As can be seen from the above, an optical modulator is obtained by forming a first waveguide and a second waveguide using two semiconductor materials of different refractive indices; the light modulator structure can effectively concentrate the mode field distribution in the waveguide to one side of the waveguide, and meanwhile, the P-type doping with higher modulation efficiency is also arranged on the side, so that the overlapping integration of the P-type doping and the mode field can be increased, and higher modulation efficiency is obtained.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the aspects of the disclosure.

Drawings

In the drawings (which are not necessarily drawn to scale), like numerals may describe similar components in different views. Like reference numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example and not by way of limitation, various embodiments discussed herein.

FIG. 1 is a schematic cross-sectional view of a first optical modulator provided in an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a second cross-sectional structure of an optical modulator provided by an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a third cross-sectional structure of an optical modulator provided by an embodiment of the present disclosure;

FIG. 4 is a schematic cross-sectional view of a fourth optical modulator provided by an embodiment of the present disclosure;

fig. 5 is a schematic implementation flow chart of a method for forming an optical modulator according to an embodiment of the disclosure;

fig. 6A to 6E and fig. 7 are schematic structural diagrams illustrating a process of forming an optical modulator according to an embodiment of the present disclosure.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without one or more of these details. In other instances, well-known features have not been described in order to avoid obscuring the present disclosure; that is, not all features of an actual implementation are described in detail herein, and well-known functions and constructions are not described in detail.

In the drawings, the size of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on" … …, "" adjacent to "… …," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" … …, "" directly adjacent to "… …," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure. When a second element, component, region, layer or section is discussed, it does not necessarily mean that the first element, component, region, layer or section is present in the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In recent years, with the development of silicon-based semiconductor technology, silicon-based optical modulators have the advantage of being capable of realizing ultra-large scale, ultra-high density, ultra-low power consumption, ultra-low cost and the like in the silicon-based optoelectronic technology field, and have gradually become the mainstream silicon photonic devices in the optoelectronic field. Not only can the silicon-based optical modulator be integrated with a single chip of electronic devices, the fabrication process of the silicon-based optical modulator is compatible with conventional CMOS (Complementary Metal Oxide Semiconductor ) processes.

The silicon-based optical modulator is one of the core devices of on-chip optical logic, optical interconnection and optical processors, and on one hand, can be used for converting radio-frequency electric signals into high-speed optical signals; alternatively, it may form a complete functional network with lasers, detectors and other wavelength division multiplexing devices.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

Referring to fig. 1, an optical modulator provided in an embodiment of the present disclosure includes, in order from bottom to top: dielectric layer 1, doped layer 2, ridge waveguide 3 located above doped layer 2, cover layer 4 located above doped layer 2 and cladding ridge waveguide 3, and first electrode 51 and second electrode 52 electrically connected with doped layer 2 throughout cover layer 4, wherein:

the doped layer 2 comprises a P-type doped region 20 and an N-type doped region 21 which are arranged in parallel;

the ridge waveguide 3 comprises a first waveguide 31 arranged on the P-type doped region 20 and a second waveguide 32 arranged on the N-type doped region 21, wherein the first waveguide 31 and the second waveguide 32 are made of semiconductor materials, and the refractive index of the first waveguide 31 material is larger than that of the second waveguide 32 material.

In practice, a first structure of the optical modulator is obtained by forming a first waveguide and a second waveguide using two semiconductor materials of different refractive indices; the light modulator structure can effectively concentrate the mode field distribution in the waveguide to one side of the waveguide, and meanwhile, the P-type doping with higher modulation efficiency is also arranged on the side, so that the overlapping integration of the P-type doping and the mode field can be increased, and higher modulation efficiency is obtained.

Here, the P-type doping process may be a diffusion method or an ion implantation method. And P-type doping is carried out on the doped layer by adopting a P-type doping process to form a P-type doped region, wherein doping ions of the P-type doping process at least comprise one of boron, indium, aluminum and gallium.

The N-type doping process may be a diffusion process or an ion implantation process. And carrying out N-type doping on the doped layer by adopting an N-type doping process to form an N-type doped region, wherein the doped ions of the N-type doping process at least comprise one of phosphorus and arsenic.

In some embodiments, referring to fig. 1-4, the ridge waveguide 3 includes a dual ridge waveguide and a single ridge waveguide.

Here, the ridge waveguide may be divided into a double ridge waveguide and a single ridge waveguide, wherein the double ridge waveguide 3 may be referred to in fig. 2, and the single ridge waveguide 3 may be referred to in fig. 1, 3, and 4.

In some embodiments, referring to fig. 2, the first waveguide 31 and the second waveguide 32 are isolated from each other, and the dimensional parameter of the first waveguide 31 is greater than the dimensional parameter of the second waveguide 32;

wherein the size parameters include: width and/or height.

In practice, a second structure of the optical modulator is obtained by forming a first waveguide and a second waveguide, which are not in contact, with two different refractive indices or with the same semiconductor material; the light modulator structure can effectively concentrate the mode field distribution in the waveguide to one side of the waveguide, and meanwhile, the P-type doping with higher modulation efficiency is also arranged on the side, so that the overlapping integration of the P-type doping and the mode field can be increased, and higher modulation efficiency is obtained.

Here, the doped layer may be etched by a dry etching process or a wet etching process to form the first waveguide, wherein the etching gas used in the dry etching process may include: trifluoromethane (CHF) ₃ ) Carbon tetrafluoride (CF) ₄ ) Hydrogen bromide (HBr) and chlorine (Cl) ₂ ). In other embodiments, the etching gas may also include other fluorocarbon-based gases, such as difluoromethane (CH) ₂ F ₂ ) Octafluoropropane (C) ₃ F ₈ ) Perfluorobutadiene (C) ₄ F ₆ ) Octafluorocyclobutane (C) ₄ F ₈ ) And octafluorocyclopentene (C) ₅ F ₈ ) One or more of them. The etching solution employed in the wet etching process may include a dilute hydrofluoric acid solution.

Referring to fig. 3, the capping layer includes a first capping region 41 corresponding to the P-type doped region 20 and a second capping region 42 corresponding to the N-type doped region 21, and a boundary between the first capping region 41 and the second capping region 42 is aligned with a boundary between the P-type doped region 20 and the N-type doped region 21;

wherein, the first covering area 41 and the second covering area 42 are made of insulating materials, and the refractive index of the first covering area 41 is different from the refractive index of the second covering area 42.

In practice, a third structure of the light modulator is obtained by forming the first and second cladding regions with two insulating materials of different refractive indices; the light modulator structure can effectively concentrate the mode field distribution in the waveguide to one side of the waveguide, and meanwhile, the P-type doping with higher modulation efficiency is also arranged on the side, so that the overlapping integration of the P-type doping and the mode field can be increased, and higher modulation efficiency is obtained.

Here, two kinds of insulating materials having different refractive indexes are deposited on the P-type doped region and the N-type doped region to form the first cladding region and the second cladding region of the cladding layer, wherein the cladding layer may be formed by any one of suitable deposition processes, for example, a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, a plasma chemical vapor deposition process, a spin coating process, a thin film process, or the like.

In some embodiments, referring to fig. 3, the refractive index of the first footprint 41 is greater than the refractive index of the second footprint 42.

In some embodiments, referring to fig. 4, the first footprint covers a first waveguide 31 having a width that is greater than a width of a second waveguide 32 covered by the second footprint.

In implementation, a fourth structure of the optical modulator is obtained by forming a first waveguide and a second waveguide of different heights and widths by using two semiconductor materials with different refractive indexes; the light modulator structure can effectively concentrate the mode field distribution in the waveguide to one side of the waveguide, and meanwhile, the P-type doping with higher modulation efficiency is also arranged on the side, so that the overlapping integration of the P-type doping and the mode field can be increased, and higher modulation efficiency is obtained.

Referring to fig. 1 to 4, a P-type doped region 20 includes three P-type doped ohmic contact regions 201, a first doped region 202 and a second doped region 203, which are sequentially arranged in parallel; the N-type doped region 21 includes three third doped regions 211, a fourth doped region 212 and an N-type doped ohmic contact region 213 which are sequentially arranged in parallel and are in contact with the second doped region 203;

wherein the doping concentration of the first doped region 202 is greater than the doping concentration of the second doped region 203;

the doping concentration of the fourth doping region 212 is greater than the doping concentration of the third doping region 211;

the first electrode 51 is electrically connected with the P-type doped ohmic contact region 201, and the second electrode 52 is electrically connected with the N-type doped ohmic contact region 213;

the first waveguide 31 is disposed in the second doped region 203 and the second waveguide 32 is disposed in the third doped region 211.

Referring to fig. 5, the method for forming an optical modulator according to an embodiment of the present disclosure may include steps S501 to S505, where:

step S501, forming an initial doping layer on the dielectric layer;

referring to fig. 6A, an initial doped layer 6 is formed on a dielectric layer 1, wherein the initial doped layer 6 employs a silicon-on-insulator (Silicon On Insulator, SOI) platform. Wherein the initially doped layer 6 comprises a first pre-set region 61 and a second pre-set region 63.

The SOI platform is composed of the following three layers: 1) A very thick bulk substrate silicon substrate layer, which serves primarily to provide mechanical support for the upper two layers; 2) A fairly thin insulating silicon dioxide interlayer; 3) A thin monocrystalline silicon top layer on which the (optical) waveguides are etched.

Step S502, etching a first preset area of the initial doping layer to form an initial first waveguide, and etching a second preset area of the initial doping layer to a preset height to form an etched second preset area;

referring to fig. 6A, the first preset region 61 of the initially doped layer 6 is etched to form an initial first waveguide 62 and an etched first preset region 611 shown in fig. 6B, and the second preset region 63 of the initially doped layer is etched to a preset height to form an etched second preset region 631 shown in fig. 6B.

Step S503, forming an initial second waveguide based on the etched second preset area;

in practice, forming an initial second waveguide based on the etched second predetermined region, comprising: the method comprises the following steps: growing a semiconductor material in a selected area on the etched second preset area to form an initial second waveguide; or, method two: and depositing a semiconductor material on the etched initial doped layer, and etching to form an initial second waveguide.

Wherein, the first method can refer to FIG. 6B, the region growth is selected on the etched second preset region 631Semiconductor material, forming an initial second waveguide 64 as shown in fig. 6C. The semiconductor material can not grow on the surface of the dielectric layer by windowing and growing at the designated position on the surface of the crystal. Where "dielectric layer surface" refers specifically to a surface upon which a semiconductor material cannot grow when the semiconductor material is selectively grown. The dielectric layer material has special performance, the semiconductor material can not form nucleus or grow on the surface of the dielectric layer material, or the nucleation rate and the growth rate are very slow, and compared with the nucleation rate and the growth rate of the semiconductor material on the surface of a single crystal, the nucleation rate and the growth rate of the semiconductor material are negligible. Typically, the dielectric layer material is an amorphous insulator material, such as silicon dioxide (SiO ₂ ) Silicon nitride (SiN), etc. In implementation, another dielectric layer (such as silicon dioxide) may be formed on the etched first preset region 611 and the etched second preset region 631 in sequence; then, removing the other dielectric layer on the target area in the etched second preset area 631, wherein the target area is an area where the initial second waveguide is to be formed; finally, semiconductor material is grown on the target region.

In the second method, referring to fig. 7, a semiconductor material is deposited on the etched first preset region 611 and the etched second preset region 631 to form a semiconductor layer 7 having a preset height, then the semiconductor layer 7 is thinned to the same height as the first waveguide 62 by a chemical mechanical polishing process, and finally the semiconductor layer 7 on the etched first preset region 611 is removed, and the semiconductor layer 7 on the etched second preset region 631 is etched to form the initial second waveguide 64 shown in fig. 6C. In practice, the predetermined height may be a height equal to or greater than the initial first waveguide dimension, and the semiconductor layer may be formed by any suitable deposition process, such as a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, a plasma chemical vapor deposition process, a spin-on process, a coating process, or a thin film process.

Step S504, P-type doping is respectively carried out on the initial first waveguide and the etched first preset region, and the first waveguide and the P-type doped region are correspondingly formed; respectively carrying out N-type doping on the initial second waveguide and the etched second preset region to correspondingly form a second waveguide and an N-type doped region; the first waveguide and the second waveguide form a ridge waveguide, and the P-type doped region and the N-type doped region form a doped layer;

referring to fig. 6C, the initial first waveguide 62 and the etched first preset region 611 are P-doped, respectively, to form the first waveguide 31 and the P-doped region 20 shown in fig. 6D; n-type doping is performed on the initial second waveguide 64 and the etched second preset region 631 respectively, so as to correspondingly form a second waveguide 32 and an N-type doped region 21 shown in fig. 6D; wherein the first waveguide 31 and the second waveguide 32 form a ridge waveguide 3, and the p-type doped region 20 and the N-type doped region 21 form a doped layer 2.

The method comprises the steps of carrying out P-type doping on an initial first waveguide and a etched first preset area by adopting a diffusion method or an ion implantation method, wherein P-type doping ions at least comprise one of boron, indium, aluminum and gallium; and carrying out N-type doping on the initial second waveguide and the etched second preset region by adopting a diffusion method or an ion implantation method, wherein N-type doping ions at least comprise one of phosphorus and arsenic.

In step S505, a cladding layer is formed on the doped layer to cladding the ridge waveguide.

Referring to fig. 6E, a cover layer 4 covering the ridge waveguide 3 is formed on the doped layer 2.

In some embodiments, referring to fig. 1 to 4, the P-type doped region 20 includes three P-type doped ohmic contact regions 201, a first doped region 202, and a second doped region 203, which are sequentially juxtaposed; the N-type doped region 21 includes three third doped regions 211, a fourth doped region 212 and an N-type doped ohmic contact region 213 which are sequentially arranged in parallel and are in contact with the second doped region 203; wherein the doping concentration of the first doped region 202 is greater than the doping concentration of the second doped region 203; the doping concentration of the fourth doping region 212 is greater than the doping concentration of the third doping region 211;

a first electrode 51 and a second electrode 52 electrically connected to the doped layer 2 are formed through the capping layer 4, including: a first electrode 51 electrically connected to the P-type doped ohmic contact region 201 is formed through the capping layer 4, and a second electrode 52 electrically connected to the N-type doped ohmic contact region 213 is formed.

In implementation, the cover layer may be etched by a dry etching process or a wet etching process to form two capacitor holes on the P-type doped ohmic contact region and the N-type doped ohmic contact region, and an electrode material is deposited in the two capacitor holes to form the first electrode and the second electrode.

The electrode material may include a metal, a metal nitride, or a metal silicide, for example, titanium nitride (TiN). In some embodiments, the electrode may be formed by depositing an electrode material in the capacitor hole by any suitable deposition process, for example, a chemical vapor deposition (Chemical Vapor Deposition, CVD) process, a physical vapor deposition (Physical Vapor Deposition, PVD) process, an atomic layer deposition (Atomic Layer Deposition, ALD) process, a plasma chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD) process, a spin-on process, a coating process, a thin film process, or the like, and embodiments of the present disclosure are not limited to the method of forming the electrode.

In order to effectively solve the technical problem of the modulation efficiency of the existing optical modulator, the present disclosure provides four different structures of an optical modulator, and the optical modulators with the four different structures can all greatly improve the modulation efficiency of the optical modulator.

In this embodiment, the silicon-based optical modulator adopts a special waveguide structure, so that light is transmitted toward one side of the waveguide when transmitted in the waveguide, and P-type doping is disposed on the side.

In this embodiment, the silicon-based optical modulator, the ridge waveguide constituting the light transmitted by the modulator, is formed by combining two waveguides having different refractive indexes. And the materials of the two waveguides with different refractive indexes are semiconductor materials.

In this embodiment, two waveguides with different refractive indexes are provided, wherein the refractive index of the material of one waveguide is greater than that of the other waveguide. The waveguide with larger material refractive index is set as P-type doping, and the waveguide with smaller material refractive index is set as N-type doping.

In this embodiment, the width of the waveguide with a larger material refractive index is greater than or equal to the width of the waveguide with a smaller material refractive index.

In this embodiment, the silicon-based optical modulator, the ridge waveguide constituting the light transmitted by the modulator, is covered with cladding layers of two different refractive indices. A boundary between the refractive index cladding layers of two different materials is located above the waveguide.

In this embodiment, the ridge waveguide is covered with cladding layers of two different refractive indices, wherein the refractive index of one of the cladding layers is greater than the refractive index of the other cladding layer. The waveguide covered by the cover layer with the material with the larger refractive index is arranged to be P-type doped, and the waveguide covered by the cover layer with the material with the smaller refractive index is arranged to be N-type doped.

In this embodiment, the width of the cladding waveguide with a larger material refractive index is greater than or equal to the width of the cladding waveguide with a smaller material refractive index.

In this embodiment, the silicon-based optical modulator is composed of two waveguides which are isolated from each other and have different widths, and the ridge waveguides which constitute the light transmitted by the modulator. The wider waveguide of the two waveguides with different widths is set as P-type doping, and the narrower waveguide is set as N-type doping.

In this embodiment, the silicon-based optical modulator is composed of two waveguides having different heights and widths, which are ridge waveguides that constitute the light transmitted by the modulator. The wider waveguide of the two waveguides with different heights and widths is set as P-type doping, and the narrower waveguide is set as N-type doping.

The above embodiments can effectively concentrate the mode field distribution in the waveguide to one side of the waveguide. The P-type doping with higher modulation efficiency is also arranged on the side, so that the overlapping integration of the P-type doping and the mode field can be increased, and higher modulation efficiency is obtained.

A logic "high" level and a logic "low" level may be used to describe the logic level of an electrical signal. Signals having a logic "high" level may be distinguished from signals having a logic "low" level. For example, when a signal having a first voltage corresponds to a signal having a logic "high" level, a signal having a second voltage corresponds to a signal having a logic "low" level. In one embodiment, the logic "high" level may be set to a voltage level higher than the voltage level of the logic "low" level. Furthermore, the logic levels of the signals may be set to be different or opposite, depending on the embodiment. For example, a signal having a logic "high" level in one embodiment may be set to have a logic "low" level in another embodiment.

In several embodiments provided by the present disclosure, it should be understood that the disclosed apparatus and methods may be implemented in a non-targeted manner. The above described device embodiments are only illustrative, e.g. the division of the units is only one logical function division, and there may be other divisions in practice, such as: multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. In addition, the components shown or discussed are coupled to each other or directly.

The units described as separate units may or may not be physically separate, and units displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

The features disclosed in the several method or apparatus embodiments provided in the present disclosure may be arbitrarily combined without any conflict to obtain new method embodiments or apparatus embodiments.

While the foregoing is directed to embodiments of the present disclosure, the scope of the embodiments of the present disclosure is not limited to the foregoing, and any changes and substitutions that are within the scope of the embodiments of the present disclosure will be readily apparent to those skilled in the art. Therefore, the protection scope of the embodiments of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. An optical modulator comprising, in order: the device comprises a dielectric layer, a doped layer, a ridge waveguide positioned on the doped layer, a cover layer positioned on the doped layer and coating the ridge waveguide, and a first electrode and a second electrode which penetrate through the cover layer and are electrically connected with the doped layer, wherein the first electrode and the second electrode are formed by the dielectric layer, the doped layer, the ridge waveguide positioned on the doped layer, the cover layer positioned on the doped layer and coating the ridge waveguide, and the first electrode and the second electrode which penetrate through the cover layer and are electrically connected with the doped layer, wherein the first electrode and the second electrode are formed by the dielectric layer, the doped layer, the ridge waveguide and the first electrode are formed by the cover layer.

The doped layer comprises a P-type doped region and an N-type doped region which are arranged in parallel;

the ridge waveguide comprises a first waveguide arranged on the P-type doped region and a second waveguide arranged on the N-type doped region, wherein the first waveguide and the second waveguide are both made of semiconductor materials, and the refractive index of the first waveguide material is larger than that of the second waveguide material.

2. The optical modulator of claim 1, wherein the ridge waveguide comprises a dual ridge waveguide and a single ridge waveguide.

3. The optical modulator of claim 1, wherein the first waveguide and the second waveguide are isolated from each other and a dimensional parameter of the first waveguide is greater than a dimensional parameter of the second waveguide;

wherein the size parameters include: width and/or height.

4. A light modulator as claimed in any one of claims 1 to 3 wherein the cap layer comprises a first cap region corresponding to the P-type doped region and a second cap region corresponding to the N-type doped region, the boundary of the first cap region and the second cap region being aligned with the boundary of the P-type doped region and the N-type doped region;

the first coverage area and the second coverage area are made of insulating materials, and the refractive index of the first coverage area and the refractive index of the second coverage area are different.

5. The light modulator of claim 4 wherein the refractive index of the first footprint is greater than the refractive index of the second footprint.

6. The optical modulator of claim 4, wherein the first footprint covers a first waveguide width that is greater than a second waveguide width that the second footprint covers.

7. A light modulator as claimed in any one of claims 1 to 3 wherein the P-doped region comprises three P-doped ohmic contact regions, a first doped region and a second doped region, arranged in series side by side; the N-type doped region comprises three third doped regions, a fourth doped region and an N-type doped ohmic contact region which are sequentially arranged in parallel and are in contact with the second doped region;

wherein the doping concentration of the first doping region is greater than the doping concentration of the second doping region;

the doping concentration of the fourth doping region is greater than that of the third doping region;

the first electrode is electrically connected with the P-type doped ohmic contact region, and the second electrode is electrically connected with the N-type doped ohmic contact region;

the first waveguide is arranged in the second doped region, and the second waveguide is arranged in the third doped region.

8. A method of forming an optical modulator, the method comprising:

forming an initial doping layer on the dielectric layer;

etching a first preset region of the initial doping layer to form an initial first waveguide, and etching a second preset region of the initial doping layer to a preset height to form an etched second preset region;

forming an initial second waveguide based on the etched second preset region;

p-type doping is respectively carried out on the initial first waveguide and the etched first preset region, and a first waveguide and a P-type doped region are correspondingly formed; respectively carrying out N-type doping on the initial second waveguide and the etched second preset region to correspondingly form a second waveguide and an N-type doped region; the first waveguide and the second waveguide form a ridge waveguide, and the P-type doped region and the N-type doped region form a doped layer;

and forming a covering layer covering the ridge waveguide on the doped layer.

9. The method of claim 8, wherein the first waveguide and the second waveguide are isolated from each other and a dimensional parameter of the first waveguide is greater than a dimensional parameter of the second waveguide;

wherein the size parameters include: width and/or height;

forming an initial second waveguide based on the etched second preset area, including: growing a semiconductor material on the etched second preset area in a selected area to form the initial second waveguide; or depositing a semiconductor material on the etched initial doped layer, and etching to form the initial second waveguide.

10. The method of claim 8, wherein the P-doped region comprises three P-doped ohmic contact regions, a first doped region, and a second doped region disposed in series and side-by-side; the N-type doped region comprises three third doped regions, a fourth doped region and an N-type doped ohmic contact region which are sequentially arranged in parallel and are in contact with the second doped region; wherein the doping concentration of the first doping region is greater than the doping concentration of the second doping region; the doping concentration of the fourth doping region is greater than that of the third doping region;

forming a first electrode and a second electrode electrically connected to the doped layer through the capping layer, comprising: and forming a first electrode electrically connected with the P-type doped ohmic contact region and a second electrode electrically connected with the N-type doped ohmic contact region through the covering layer.